Add deprecation warnings for permission API usage from iframes

third_party/WebKit/Source/modules/encryptedmedia/NavigatorRequestMediaKeySystemAccess.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/encryptedmedia/NavigatorRequestMediaKeySystemAccess.h"
 
 #include <algorithm>
 
 #include "bindings/core/v8/ScriptPromise.h"
 #include "bindings/core/v8/ScriptPromiseResolver.h"
@@ skipping 309 matching lines @@
   // 3. Let document be the calling context's Document.
   //    (Done at the begining of this function.)
   if (!document->GetPage()) {
     return ScriptPromise::RejectWithDOMException(
         script_state,
         DOMException::Create(
             kInvalidStateError,
             "The context provided is not associated with a page."));
   }
 
+  Deprecation::CountDeprecationCrossOriginIframe(

[iclelland, 2017/06/22 15:12:48]

This appears to print a deprecation message (and count usage) on every use of
requestMediaKeySystemAccess -- is that correct? Can we restrict the count to
just cases where the method was actually called in a cross-origin context, and
was blocked?

By M61, I'd like to have also distinguish between the cases where it was
implicitly blocked because no positive-policy was present, and the case where it
was explicitly blocked by a header policy, but we don't have the logic in place
for that yet.

[raymes, 2017/07/05 01:04:25]

Updated to only count if:
-Disabled by FP, and
-In cross-origin iframe

Also added a comment about the ideal behavior

+      *document, WebFeature::kEncryptedMediaDisabledIframe);
+
   // 4. Let origin be the origin of document.
   //    (Passed with the execution context.)
 
   // 5. Let promise be a new promise.
   MediaKeySystemAccessInitializer* initializer =
       new MediaKeySystemAccessInitializer(script_state, key_system,
                                           supported_configurations);
   ScriptPromise promise = initializer->Promise();
 
   // 6. Asynchronously determine support, and if allowed, create and
   //    initialize the MediaKeySystemAccess object.
   MediaKeysController* controller =
       MediaKeysController::From(document->GetPage());
   WebEncryptedMediaClient* media_client =
       controller->EncryptedMediaClient(execution_context);
   media_client->RequestMediaKeySystemAccess(
       WebEncryptedMediaRequest(initializer));
 
   // 7. Return promise.
   return promise;
 }
 
 }  // namespace blink